<template>
  <div class="hello">
    <h1>{{ msg }}</h1>
    <template>
        <div>
          <input
            ref="excel-upload-input"
            class="excel-upload-input"
            type="file"
            accept=".xlsx, .xls"
            @change="handleClick"
          />
          <div
            class="drop"
            @drop="handleDrop"
            @dragover="handleDragover"
            @dragenter="handleDragover"
          >
            拖拽上传文件
            <el-button
              :loading="loading"
              style="margin-left:16px;"
              size="mini"
              type="primary"
              @click="handleUpload"
            >点击上传</el-button>
          </div>
          <el-table
            :data="tableData"
            border
            highlight-current-row
            style="width: 100%;margin-top:20px;"
          >
            <el-table-column v-for="item of tableHeader" :key="item" :prop="item" :label="item" />
          </el-table>
        </div>
      </template>
  </div>
</template>
<script>
import Vue from 'vue'
import XLSX from 'xlsx'
Vue.use(XLSX)
export default {
  name: "HelloWorld",
  props: { msg: String, msg1: String,onSuccess: Function },
  data() {
    return {
      tableData: [],
       loading: false,
      tableData: [],
      tableHeader: []
    };
  },
  methods: {
    handleDrop(e) {
      e.stopPropagation()
      e.preventDefault()
      if (this.loading) return
      const files = e.dataTransfer.files
      if (files.length !== 1) {
        this.$message.error('仅支持单个上传一个文件')
        return 
      }
      const rawFile = files[0] // 获取文件信息
      if (!this.isExcel(rawFile)) { //是不是excel文件
       this.$message.error('Only supports upload .xlsx, .xls, .csv suffix files')
       return false
      }
      this.upload(rawFile)
      e.stopPropagation()
      e.preventDefault()
    },
    handleDragover(e) {
      e.stopPropagation()
      e.preventDefault()
      e.dataTransfer.dropEffect = 'copy'
    },
    handleUpload() {
      this.$refs['excel-upload-input'].click()//触发表单上传事件，跳出选择文件框
    },
    handleClick(e) {
      // console.log(e);
      const files = e.target.files
      const rawFile = files[0] // only use files[0]
      if (!rawFile) return
      this.upload(rawFile)
    },
    upload(rawFile) {
      this.$refs['excel-upload-input'].value = null // fix can't select the same excel
      if (!this.beforeUpload) {
        this.readerData(rawFile)
        return
      }
      const before = this.beforeUpload(rawFile) //判断文件上传大小
      if (before) {
        this.readerData(rawFile) //把excel转化成数组
      }
    },
     beforeUpload(file) {
      const isLt1M = file.size / 1024 / 1024 < 1
      if (isLt1M) {
        return true
      }
      this.$message({
        message: '请不要上传大于1M的文件',
        type: 'warning'
      })
      return false
    },
    readerData(rawFile) {
      this.loading = true
      return new Promise((resolve, reject) => {
        const reader = new FileReader()
        reader.readAsArrayBuffer(rawFile)
         //参数可以是 Blob 或者 File 对象异步结果将在onload 事件中体现
        reader.onload = e => {
          const data = e.target.result 
          console.log(data);
          const workbook = XLSX.read(data, { type: 'array' }) 
          console.log("workbook",workbook);
          //看下图
          const firstSheetName = workbook.SheetNames[0]
          // console.log("firstSheetName",firstSheetName);// "SheetJS" 取出工作表名称
          const worksheet = workbook.Sheets[firstSheetName] //取出工作表名称对应的表格数据
          const header = this.getHeaderRow(worksheet) //表头名
          // console.log("header",header);
          const results = XLSX.utils.sheet_to_json(worksheet)//输出数据，除去表头
	        //{timestamp: "2017-01-01 07:37:20",title: "Mtiwxlj Cqcdg Hvbjijr Vgmeey Wwznq Ljjnkvbz",
			//type: "US",importance: 2,status: "draft"} results的其中一列数据
          this.tableData = results;
          this.tableHeader= header;
          this.loading = false
          resolve()
        }
      })
    },
    getHeaderRow(sheet) {
      const headers = []
      const range = XLSX.utils.decode_range(sheet['!ref']) //!ref: "A1:E21"
      // console.log(range);
      // s: {c: 0, r: 0} 开始为A1
      // e: {c: 4, r: 20} 结束为 E21
      let C
      const R = range.s.r
      /* start in the first row */
      for (C = range.s.c; C <= range.e.c; ++C) { /* walk every column in the range */
        const cell = sheet[XLSX.utils.encode_cell({ c: C, r: R })]
        // console.log(cell); A1的对象的值
        /* find the cell in the first row */
        let hdr = 'UNKNOWN ' + C // <-- replace with your desired default
        if (cell && cell.t) hdr = XLSX.utils.format_cell(cell)
        // console.log(XLSX.utils.format_cell(cell));//每个头部名
        headers.push(hdr)
      }
      return headers
    },
    isExcel(file) {
      return /\.(xlsx|xls|csv)$/.test(file.name)
    }
  }
  
};
</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped lang="less">
h3 {
  margin: 40px 0 0;
}
ul {
  list-style-type: none;
  padding: 0;
}
li {
  display: inline-block;
  margin: 0 10px;
}
a {
  color: #42b983;
}
</style>
